With the rapid development of Internet and popularity of big screen multi-function mobile phones, plenty of mobile data multimedia services have come forth and various high bandwidth multimedia services are constantly emerging, such as video conference, television broadcast, video on demand, advertisement, online education, interactive game, and so on, which satisfies the growing service demand of mobile users on the one hand, and brings a new business growth point for mobile operators on the other hand. These mobile multimedia services require that multiple users are able to simultaneously receive the same data, which compared with general data, has characteristics such as large data amount, long duration and delay sensibility.
For effective utilization of mobile network resource, the 3rd Generation Partnership Project (referred to as 3GPP for short) proposes the Multimedia Broadcast Multicast Service (referred to as MBMS for short) which is a technique in which data is sent from one data source to multiple targets so that the network (including the core network and access networks) resource is shared and the utilization ratio of the network resource (especially the air interface resource) is improved. The MBMS defined in the 3GPP not only can implement low-speed multicast and broadcast of plain text messages, but also can implement high-speed broadcast and multicast of multimedia services, to provide a wide variety of video, audio and multimedia services, which undoubtedly complies with the future development trend of mobile data, and provides a better business prospect for 3G development.
Configuration of a radio bearer of MBMS services can adopt bearer types such as P-T-M (Point-To-Multipoint, also abbreviated to PTM or ptm) and P-T-P (Point-To-Point, also abbreviated to PTP or ptp).
The PTM mode of a MEMS service uses the common logical channel MTCH (MBMS PTM Traffic Channel) to send data to user equipments (UE) that have joined the multicast service or are interested in the broadcast service, the term UE in this specification is generalized and includes all kinds of wireless terminals such as mobile stations (MS) in other wireless communication systems; the MTCH logical channel is mapped to the transmission channel FACH (Forward Access Channel) and sent in a radio interface via the physical channel Secondary CCPCH (Secondary Common Control Physical Channel, referred to as SCCPCH for short). The RNC (Radio Network Controller) at the system side informs UEs of configuration information associated with MBMS service configuration, such as physical channels, via the MCCH (MBMS point-to-multipoint Control Channel) channel.
Messages associated with MBMS sent on the MCCH comprise: MBMS Access Information, MBMS Common p-t-m rb Information, MBMS Current Cell p-t-m rb Information, MBMS General Information, MBMS Modified services Information, MBMS Unmodified services Information, and so on.
In current MBMS protocol, a Method for sharing physical channel resource by time division multiplexing in a PTM transmission mode is defined. In this method, multiple services are mapped to different MTCH logical channels, and different logical channels are mapped to the same or different FACH transmission channels. Different transmission channels are mapped to the same or different SCCPCH physical channels. This method defines a group of cells for each service, and the group of cells defines the time of channel occupation by the service. Different services share the channel resource by time division multiplexing. Said “share” herein may be that multiple logical channels are mapped to the same transmission channel, or multiple transmission channels are mapped to the same physical channel, and in the above two modes, different services (logical channels) are sent at different time, and there is only one service being sent at one time point. UEs receive different services at different time.
The above time division multiplexing mode is embodied in the MBSFN TDM Info List cell in the MBMS Current Cell p-t-m rb Information message. In said cell, the following parameters are defined for each MBMS service of time division multiplexing:
TDM Rep, this parameter is defined as a repetition period and is represented by the number of TTIs in the repetition period. Different services are configured with different repetition period lengths, and the parameter is configured in a relatively fixed way, that is, it is configured through the TDM Req parameter of each service. Each service occupies the resource for a certain time length in a repetition period. The resource allocation situation is consistent in different repetition periods.
TDM Offset, this parameter is defined as the initial offset time of channel resource occupation by a MBMS service in a repetition period.
The channel resource occupied by a MBMS service is defined as follows:(CFN div N)mod TDM_Rep=TDM_Offset
Wherein, N is the number of system frames (such as 10 ms frame) included in a TTI, said TTI (Transmission Time Interval) is the transmission time interval of the FACH transmission channel to which the MTCH service logical channel is mapped, and the value is an integral multiple of the time length of a system frame. The CFN is the connection frame number of a system frame, and each 10 ms frame transmitted on the FACH channel has a CFN, of which the value range is defined as 0 to 255. (CFN div N) is an aliquot arithmetic expression that represents rounding down. Said system frame may also be referred to as radio frame.
The original protocol may cause resource allocation difficulty in some cases.